Cluster
In plain terms
A group of machines working together as one system.
Going deeper
A cluster pools multiple nodes so they can be managed and scheduled collectively for scalability and resilience. It presents many machines as one resource.
Under the hood
A control plane coordinates worker nodes; clustering underpins distributed and orchestrated systems.
Examples
Kubernetes clusters, database clusters, compute clusters, high availability.
Think of it like...
Like a team of workers coordinated as a single crew rather than acting alone.